These days we are using  LCD, Plasma, LED and OLED TV sets. There was a time when everybody used Cathode Ray Tube (CRT) sets. Even now many sets in rural areas are CRT sets. We shall discuss one by one the technology behind all these sets. We commence by first concentrating on CRT sets. To understand the concept of CRT, let us understand what an Electronic Gun is.

The electrical charges in the caesium dots will be released with some assistance. Each tiny charge must set up currents which could be amplified and transmitted as elecro-magnetic radio waves. This is accomplished by an electronic gun. It shoots out a beam of electrons. There are magnetic deflector coils in the muzzle of the gun. The gun can sweep the beam of electrons back and forth by its adjustment. The electron beam moves as the eyes do while reading, from left to right. This sweeping action is called scanning.

The mosaic screen is scanned fifty times every second. It releases the various electrical charges from the caesium dots while it passes over them. These charges are sent to an amplifier to make them stronger. Ultimately, they are transformed into electro-magnetic waves. These are sent across the transmission antenna.. As the charge is higher or lower on the caesium dots, the electron beam too produces a corresponding small or large electric current while scanning the dots.